Method of making a porous sponge-like formulation, a porous sponge-like formulation, use of porous sponge-like formulation and a product comprising the foamed sponge-like formulation

ABSTRACT

The present invention relates to a method of making a porous sponge-like formulation that can well absorb water, oil and organic solvents separately or combined. Methods of preparing said formulation and its use in medical, pharmaceutical, biotechnological, chemical as well as in wound care, home care, (agro-)environmental and construction material applications are also provided.

STATE OF THE ART

Artificial sponge-like structures are being applied for varioustechnical challenges in food, cosmetics, or pharma industries as well asfor energy storage, waste water treatment or in home care, wound care aswell as agricultural and construction material applications. The highporosity of these sponge structures results in a high surface-to-volumeratio and thus in the possibility to interact with the surrounding, in alow density and thus light weight and in the ability to passively oractively take up liquids. The replacement of synthetic polymers bybiopolymers as bulk material enhances the biodegradability, renewabilityand recyclability of related products/materials.

Various processes are described to generate biodegradable sponge-likestructures for absorption based separation applications, e.g. foroil-water separation.

Both (A) CN108273476 A (alginate-protein sponge) as well as (2)WO2015056273 A1 (seaweed-polysaccharide sponge) or (3) Duan, Bo, et al.“Hydrophobic modification on surface of chitin sponges for highlyeffective separation of oil” ACS applied materials & interfaces 6.22(2014): 19933-19942 (chitin sponge) prepare mixtures with biopolymers,perform cross-linking with chemical additives, followed byfreeze-drying/lyophilization to generate a dry porous oil-absorbingstructure.

Aerogels based on cellulose fibers can be amphiphile absorbents, henceabsorbing water, oil or organic solvents, as e.g., described by (4)Jiang, Feng, and You-Lo Hsieh. “Amphiphilic superabsorbent cellulosenanofibril aerogels”, Journal of Materials Chemistry A 2.18 (2014):6337-6342. Also these porous structures were produced by freeze-drying.

Other processes for the production of absorbents include chemicalpolymerization, washing with solvents followed by vacuum drying, e.g.,(5) Zhu, Haiguang, et al. “A robust absorbent material based onlight-responsive superhydrophobic melamine sponge for oil recovery.”Advanced Materials Interfaces 3.5 (2016): 1500683. (6) M. Betz, C. A.Garcia-Gonzalez, R. P. Subrahmanyam, I. Smirnova, U. Kulozik,Preparation of novel whey protein-based aerogels as drug carriers forlife science applications, The Journal of Supercritical Fluids, Volume72, 2012, Pages 111-119, ISSN 0896-8446 and (7) Selmer, Ilka, et al.“Development of egg white protein aerogels as new matrix material formicroencapsulation in food.” The Journal of Supercritical Fluids 106(2015): 42-49 describe the production of pure protein aerogels stable inwater and with the ability to absorb water. These protein aerogels areproduced by applying a heating step followed by freeze-drying orsupercritical carbon dioxide drying.

(8) V. Perez-Puyana, M. Felix, A. Romero, A. Guerrero, Development ofeco-friendly biodegradable superabsorbent materials obtained byinjection moulding, Journal of Cleaner Production, Volume 198, 2018,Pages 312-319, ISSN 0959-6526 try to apply a more scalable injectionmoulding process to produce absorbents based on proteins. The processhowever requires the addition of nanoclay particles and plasticizer.

All production processes for absorbents based on proteins described inliterature require either time-, energy and cost-intensive dryingmethods such as freeze-drying, supercritical carbon dioxide drying orvacuum drying and/or the utilization of additives such as chemicalcross-linking agents, fillers, etc. Further, the so far describedsponge-like products received from such described production processespreferably absorb either water or oil based liquids.

SUMMARY OF THE INVENTION

The invention relates in general to a method of making a poroussponge-like formulation that can absorb water, oil and organic solvents,said method comprising the steps:

-   -   Preparing a protein dispersion in water;    -   Dispersing gas in the protein dispersion to form a foam        structure;    -   Optionally moulding into a shape;    -   Expansion of the foam structure;    -   Volumetric electromagnetic heating;    -   Optionally drying; and    -   Optionally cutting into pieces.

The invention further relates to a porous sponge-like formulationcomprising protein, preferably obtained by a method as described herein.

The invention further relates to the use of a porous sponge-likeformulation as described herein in a non-food product.

The present invention relates to a method of making a porous sponge-likeformulation that can absorb water and oil, said method comprising thesteps:

-   -   Preparing a 5-60 wt % protein dispersion in aqueous liquid,        preferably in water;    -   Dispersing gas in the protein dispersion to form a foam        structure;    -   Optionally moulding or shaping to form a foam structure;    -   Expansion of the foam structure;    -   Volumetric heating induced water evaporation and protein        denaturation;    -   Optionally drying; and    -   Optionally cutting into pieces.

In some embodiments, 10-50 wt % protein dispersion is prepared in water,preferably 15-45 wt % protein dispersion.

In some embodiments, the protein is a globular protein, preferably aplant protein.

In some embodiments, the protein dispersion is a homogenous dispersion.

In some embodiments, the protein dispersion is a whey protein isolatedispersion.

In some embodiments, the protein dispersion further comprises fibre, forexample, fibrillated or crystalline cellulose.

In some embodiments, the protein dispersion further comprisesplasticisers for example sugar, and/or hydrocolloid.

In some embodiments, the protein dispersion further comprises fillers,for example clay particles.

In some embodiments, gas is dispersed in the protein dispersion using arotating membrane foaming device.

In some embodiments, said foam structure has a gas volume fraction of10-90 vol %, preferably 40-80 vol %, most preferably 60-75 vol %.

In some embodiments, the foam structure is increased to above theprotein denaturation temperature.

In some embodiments, the temperature gradient between the core and thesurface layer of the foam structure is between −0.1 and 0.3, preferablybetween −0.1 and 0.2, more preferably between −0.1 and 0.1.

In some embodiments, heating is volumetric preferably throughapplication of electromagnetic waves, preferably microwave power.

In some embodiments, a vacuum is applied before and/or during dryingwhich is between 10-800 mbar, preferably 50-500 mbar, more preferablybetween 100-300 mbar.

In some embodiments, said porous sponge-like formulation has open poreshaving an average pore diameter of up to 500 microns, preferably up to200 microns.

The invention further relates to a porous sponge-like formulation thatcan absorb water and oil and comprises protein, obtained by a method asdescribed herein.

The invention further relates to a foamed porous sponge-like formulationthat can absorb water, oil and organic solvents and comprises protein,wherein the porous formulation has a water content <15 wt % after dryingand has a porosity of between 10-95 vol %, preferably 80-95 vol %; andwherein said formulation can absorb water and oil without disintegratingor dissolving to an extent of less than 10 wt %.

In some embodiments, the moisture content of the porous sponge-likeformulation is less than 60 wt %, preferably less than 20 wt %, morepreferably less than 10 wt %.

In some embodiments, said formulation further comprises fibres and/orother biopolymers, for example polysaccharides.

In some embodiments, said formulation is capable of absorbing water, oiland organic solvent at substantially the same velocity.

In some embodiments, said formulation is capable of absorbing water at avelocity of up to 2.2 mm/s, preferably up to 5 mm/s at 0-100° C. andwithout structure disintegration

In some embodiments, said formulation is capable of absorbing water witha temperature of 0-100° C. to an extent that up to 140% of pore volumeis filled with water due to additional structural swelling effects.

In some embodiments, said formulation is capable of absorbing oil at avelocity of up to 1.5 mm/s, preferably up to 5 mm/s at 0-200° C. withoutstructure disintegration or filling the formulation structure up to 90%of pores, preferably up to 95% of pores, most preferably up to 100% ofthe pore volume with oil with a temperature of 0-200° C.

In some embodiments, said formulation is elastic-plastically deformableafter absorption of water and is elastic-brittle in substantially drystate and after absorption of oil or ethanol, methanol, acetone,dimethyl sulfoxide and toluene.

The invention further relates to use of the porous sponge-likeformulation as described herein in a product, for example a wound carerelated secretion absorber material.

The invention further relates to use of the porous sponge-likeformulation as described herein in a product, for example a as filterand/or absorber for the cleaning of watery and/or oil-based fluidsystems and/or water/oil mixtures.

The invention further relates to use of the porous sponge-likeformulation as described herein in a product, for example for medicalsurgery applications to enable larger amounts of blood or secretionfluid uptake.

The invention further relates to use of the porous sponge-likeformulation as described herein in a product, for example for cosmeticsapplications with water/oil-based liquid and skin care ingredients orskin cleaning fluids release from and/or uptake into the sponge-likeproduct.

The invention further relates to use of the porous sponge-likeformulation as described herein in a product, for example for theencapsulation of active/functional ingredients from the categories:flavors, aromas, micronutrients, antioxidants, agro-chemicals,chemicals, washing agents, drugs, pre-/probiotic cultures, skin carecomponents, cleaning components.

The invention further relates to use of the porous sponge-likeformulation as described herein in a product, for example as templatefor cell culturing.

The invention further relates to use of the porous sponge-likeformulation as described herein in a product, for example applied in oneof the areas of medicine, pharmacology, biotechnology, chemistry as wellas in home care, wound care, (agro-) environmental and constructionmaterial applications.

The invention further relates to use of the porous sponge-likeformulation as described herein in a product, for example asimmobilization carrier for microorganisms in biotechnological,pharmaceutical and/or medical applications.

The invention further relates to a wound care related product comprisingthe porous sponge-like formulation as described herein.

DETAILED DESCRIPTION OF THE INVENTION Definitions

The following definitions are provided for the technical features usedthroughout the specification.

Sponge-like denotes a porous structure with 5-95% porosity and up to100% of open pore or pore channel structure, which allows for thepassive or active absorption of a liquid into the porous structure.

Heat induced expansion denotes an increase of aerated product porevolume by more than 25%, preferably more than 50% upon heating and vaporpressure generation.

Protein denaturation through heating denotes unfolding or dissociationof the protein structure induced by heat, followed by re-associationand/or aggregation. The transition from native to denatured state isassociated with an alteration in secondary and tertiary structure of theprotein through rupture of hydrogen bonds, ionic interactions andcleavage of disulfide bridges.

Volumetric heating denotes heating of an entire volume (center tosurface) of a structure or product, e.g., by application ofelectromagnetic waves, such as microwaves, which penetrate into thestructure resulting in heat dissipation. This is in contrast to heatingby convection or conduction, which leads to heating of the surface andsubsequent heat transfer from the surface toward the center.

Electromagnetic waves or radiation denote waves of an electromagneticfield propagating through space and carrying electromagnetic radiantenergy. It includes radio waves, microwaves, infrared, visible light,ultraviolet, X-rays and gamma-rays.

The temperature gradient or relative temperature gradient denotes thetemperature difference between the geometric center of the cross-section(in radial direction) and the temperature in the surface layer dividedby the center temperature (Temp. gradient=(Tcenter−Tsurface)/Tcenter. Itwas assessed by measuring the temperature in the geometric center and inthe surface layer at maximum half the radius of the moulded or shapedfoam structure by means of fiber-optic temperature sensors.

Disintegrating means breaking into more than one piece, for exampleafter the porous sponge-like formulation is immersed in a liquid.

Protein denotes plant and/or animal based bio-macromolecules, consistingof one or more long chains of amino acid residues. A protein istypically a polymer consisting of 50 or more amino acid residues linkedby peptide bonds. Examples of proteins of the invention are wheyprotein, egg white protein, pea protein, and soy protein.

Fibre denotes non-starch polysaccharides with 10 or more monomericunits. The solubility of a fibre is determined by the relative stabilityof the ordered and disordered form of the polysaccharide. Molecules thatfit together in a crystalline array are likely to be energetically morestable in solid state than in solution. Hence, linear polysaccharides,i.e., cellulose, tend to be insoluble (non-soluble), while branchedpolysaccharides or polysaccharides with side chains, such as pectin ormodified cellulose, are more soluble. Hence, non-soluble fibre denotesfibre with low or no solubility in water. This might however containresidues of soluble fibre due to the production/extraction process.Soluble fibre denotes dietary fibre with high solubility such as pectin.Examples of non-soluble fibres of the invention are cellulose fibre, forexample citrus fibre, microfibrillated cellulose or microcrystallinecellulose.

When a composition is described herein in terms of wt %, this means amixture of the ingredients on a dry basis, unless indicated otherwise.

Porosity denotes the fraction of pore volume in the entire volume of theporous sponge-like formulation, wherein the pore volume denotes theaccumulate volume of all pores.

Brittle denotes fracturing upon exceeding the elastic deformation limitwithout undergoing plastic deformation.

Elastically and plastically deforming or elastic-plastic deformation ofporous solids denotes elastic deformation followed by plastic yieldingof the structure and stands in contrast to brittle crushing of thestructure. The elastic part of the deformation is typically reversible,while the plastic part is typically irreversible.

The terms “comprising”, “comprises” and “comprised of” as used hereinare synonymous with “including” or “includes”; or “containing” or“contains”, and are inclusive or open-ended and do not excludeadditional, non-recited members, elements or steps. The terms“comprising”, “comprises” and “comprised of” also include the term“consisting of”.

As used herein the term “about” means approximately, in the region of,roughly, or around. When the term “about” is used in conjunction with anumerical value or range, it modifies that value or range by extendingthe boundaries above and below the numerical value(s) set forth. Ingeneral, the term “about” is used herein to modify (a) numericalvalue(s) above and below the stated value(s) by 10%.

Substantially dry denotes drying to an extent that the water content isbelow 12 wt %.

Substantially the same velocity during absorption of oil and waterdenotes a relative difference in velocity of not more than 200% at sameliquid viscosity, given that water and oil might not show the samewettability towards the porous sponge-like formulation nor the samesurface tension toward air.

Method of Making a Porous Sponge-Like Formulation

The formulation is made by foaming a highly-concentrated proteindispersion followed by volumetric heating and drying. Depending on theviscosity of the protein dispersion, the foaming step may be performedby extrusion foaming, membrane foaming or other foaming techniques. Thefoam structure is optionally moulded or shaped followed by heating andoptionally drying by controlled volumetric heating through superpositionof electromagnetic heating, e.g., microwave, and hot air. Volumetricheating such as generated by microwave results in quick steam generationand accumulation in the foam bubbles causing expansion of the foamstructure. At the same time, heating causes fast denaturation of theproteins at the bubble interface and in the foam lamellae. Controlledmicrowave power input and hot air temperature allow for a generation ofa homogeneous temperature distribution throughout the structure. Thisleads to a homogeneous expansion, denaturation and continuous transportof moisture from the material to the surface and surrounding and thus toa late crust formation. The foam bubbles expand to an extent that theycoalesce and form open channels throughout the structure. The resultingdry open-porous and stiff structure adsorbs water and/or oil tocomparable extents given by the accessibility of both hydrophilic andhydrophobic parts of the intrinsically amphiphilic proteins. Otherheating methods can be used, which allow for volumetric heating, such asinfrared heating and Ohmic heating.

Porous Sponge-Like Formulation

The dry foam sponge material of the invention, upon contact with aliquid phase (aqueous or oil phase), can take up the liquid and releaseit again upon applying a stress or upon suction to it. The dried foam,denoted also as dry sponge, is preferably made out of globular proteinsthat denature upon heat treatment, such as whey protein or whey proteinisolate. Other globular proteins can also be used. The dry spongeadsorbs the liquid without disintegrating the sponge structure and maythus be applied as a dried foamed material that is able to take up andrelease a liquid and hold it and release it upon mechanical stressimpact.

The sponge material can absorb both aqueous and oily phases. The spongemechanics can be modulated by tailoring the density or by addingadditional fibres and/or other additives.

Product

The material can be applied in various products to introduce some liquidsucking, holding and controlled release characteristics. The latter canrelate to the fluid and/or functional components added or contained inthe fluid.

This includes the four main categories of:

(1) Using the product for sucking and/or immobilizing a liquid or liquidmixture:This can be relevant for cleaning or separation processes including thecleaning of wound surfaces from secreted wound fluid or blood. Thisfurther includes applications where the product, also in refinedsponge-particle form can be added to a matrix material (e.g.construction material) from which contained liquid shall be taken up forstiffening the matrix material.(2) Release of product entrapped liquid or of components contained insuch liquid:This can be of interest for the release of functional components totrigger a physiological, biological or chemical reaction in thesurrounding/surrounding material (e.g. wound healing support;disinfection/sanitizing; cosmetics function; cleaning function; perfumeor skin cream delivery(3) Use of product structure as template for culturing:This is expected to be relevant for cell culturing (skin, organs,meat/meat replacers)(4) Use for immobilizing microorganisms or cells to enable improvedbiotechnological processing (e.g. for pharmaceutical or medicalapplications).

EXAMPLES Example 1

Whey protein sponge production and comparison to pure hot air dryingAbout 40 wt % whey protein isolate was dispersed in tap water andhydrated overnight. The dispersion was foamed by dispersing gaseousnitrogen in the protein dispersion with a rotating membrane foamingdevice. The resulting protein foam had a gas volume fraction of 70 vol %and a number weighted mean bubble size d50, 0=54 um with a span of 1.28(measure for bubble size distribution width, defined as (x90, 0−x10,0)/x50, 0).

About 24 mL of the foam was filled into cylindrical transparentpolypropylene moulds with a diameter of 27.5 mm and a height of 86 mm.The samples (4 samples per trial) were dried at a microwave power of 100W and a hot air temperature of 60° C. for over 2 hours or at a microwavepower of 50 W and a hot air temperature of 60° C. over 3 hours. Theresulting dry foam with a diameter of 20 mm and a height of 70-85 mm,shown in FIGS. 1 (B) and (C), can be removed from the mould and furtherprocessed, for example by cutting into pieces.

For comparison, FIG. 1 (A) shows the same foam dried withoutsuperposition of microwave only with hot air at a temperature of 100° C.over 3 hours. It has a heterogeneous, wrinkled, partly shrunkenstructure with a darker outer crust.

Measuring the temperature of the foam structure during heating anddrying in the radial center and in the surface layer, showed theimportance of a homogeneous temperature gradient during the heating anddrying process. FIG. 2 shows the time-dependency of the relativetemperature gradient inside the foam structure (in %), defined astemperature difference between the geometric radial center and thesample surface layer related to the center temperature. Pure hot airdrying leads to a highly negative temperature gradient, meaning that thesurface heats up much faster than the center. In contrast, superpositionof microwave caused a faster heating of the core and in particular asignificantly more even heating throughout the entire cross section ofthe foam product. This results accordingly in an even expansion, proteindenaturation and water transport during drying and thus minimisesevaporation-induced uneven shrinkage resulting in the generation of ahomogeneous porous structure.

Scanning electron microscopy images of the same samples (A) and (B)shown in FIG. 3 reveal a denser crust and a sheet-like structure whendrying with hot air only (A) and an open-porous surface and porestructure with spherical pores when drying with superimposed microwaveand hot air (B). The spherical pores are foam bubbles retainedthroughout the heating and drying process. On top of the structuraldependency from the drying process a more even protein denaturationdistribution across the sample cross section has to be counted with incase of the coupled Microwave/convection drying.

Example 2

Whey Protein Porous Sponge-Like Formulation Absorbing Water and Oil

A sponge piece of 20 mm height of sample (C) (100 W/60° C.) in Example1, with a density of 0.09 g/cm³, shown in FIG. 4 in water (left, stainedwith food colorant) and in oil (right), absorbed 15 g water ((η=1 mPas;ρ=1.0 g/cm³) and 9 g low-viscous silicon oil (η=3 mPas; ρ=0.9 g/cm³) perg sample at a velocity of approximately 2.2 mm/s for water andapproximately 1.5 mm/s for oil. Assuming a solid density of whey proteinisolate of 1.4 g/cm³, the density of the dry porous structure of 0.09g/cm³ corresponds to a porosity of 94%. Hence, at the measured oilabsorption capacity, 94% of the pore volume in the dry porous structuremust get filled with oil. In contrast, the water filled up over 140% ofthe pore volume (see FIG. 5), meaning that the porous sponge-likeformulation swells upon absorption of water.

Absorption of water into the whey protein sponge structure causessoftening, whereas the sponge remains brittle and stiff upon absorptionof oil. FIG. 6 shows the mechanical properties in compression of awater-filled and an oil-filled whey protein sponge at a compressionvelocity of 0.02 mm/s.

As the sponge softens upon absorption of water, the water can be pressedout, e.g., by hand, and the sponge can be refilled. The weight ofabsorbed water decreased by not more than 15% over 50 compression andre-absorption cycles, as shown in FIG. 7.

A sponge filled with oil cannot be compressed and re-filled due to thebrittle structure. The oil could however be removed by suction, e.g., byvacuum. Alternatively, the sponge can be softened by absorption ofwater, subsequently the water is squeezed out and the sponge is immersedin oil. Thus, the sponge structure is soft and elastic and the absorbedoil can be squeezed out by hand. This porous sponge-like formulation canbe used for example for carrying liquid products (water based cosmeticsi.e. body lotions and perfumes), for water holding fertilizer pellets,or as absorbent for cleaning.

Example 3

Production of Soy Protein Sponge

About 18 wt % soy protein isolate was dispersed in tap water andhydrated overnight; foamed with a kitchen machine (Kitchen Aid) to reacha gas volume fraction of approximately 20 vol %; the foam wasdistributed onto a Teflon plate in portions of 2 table spoons and driedat 50 W and 60° C. over 1 hours. The resulting stiff sponge structureabsorbed water, oil and organic solvents separately, combined or inseries without disintegrating and softened when filled with water.

Example 4

Whey Protein Sponge Reinforced with Citrus Fibres

About 40 wt % whey protein isolate and 5 wt % citrus fibres weredispersed in tap water and hydrated overnight. The dispersion was foamedin a kitchen machine (Kitchen Aid) to reach a gas volume fraction of 40vol %. Approximately 24 mL of the foam were filled into cylindricaltransparent polypropylene moulds with a diameter of 27.5 mm and a heightof 86 mm. The samples were dried at a microwave power of 100 W and a hotair temperature of 60° C. over 2 hours. The resulting dry sponge absorbsboth water, oil and organic solvent and is stiffer and stronger comparedto the pure whey protein sponge.

Example 5

Whey Protein Sponge Filled with Agar Agar Solution

200 mL cranberry juice (for colour contrast) were mixed with 0.7 g agaragar powder, heated to boiling for 1 min. A whey protein sponge producedas described in Example 2 was soaking in the hot cranberry juice-agaragar mixture. The juice was immediately absorbed into the spongestructure (FIG. 8). The filled sponge was cooled for 4 h at 4° C. tocause gelation of the cranberry juice-agar agar mixture.

For comparison, cranberry juice gel was produced with the sameconcentration of agar agar powder by moulding into a plastic beaker andcooling. The cranberry juice gel was not self-sustaining without themould.

The stiffness of the gel-filled sponge and the pure gel was compared bytexture analysis by compression and penetration, respectively, as shownin FIG. 9 at a velocity of 0.5 mm/s. Although the sponge structure makesup below 10 wt % of the gel-filled sponge (>90 wt % cranberry juicegel), the Young's modulus, a measure of stiffness, increases fromapproximately 35 Pa to 1500 Pa compared to the pure gel. The Young'smodulus was determined as slope in the linear regime at a strain of6-8%. The initial part of the stress-strain curve (strain=0-5%) showstailing due to the slightly uneven surface of the sample and was thusnot considered.

The gel structure is highly reinforced by the protein scaffold. The gelcould be further loaded with an active substance for pharmaceutical oragrochemical applications. The protein sponge provides mechanicalstability and integrity. The elasticity of the sponge structure whenbeing filled with an aqueous liquid allows for multiple loading andrelease cycles.

Example 6

Production of Sponge Particles without Mould

40 wt % whey protein isolate was dispersed in tap water and hydratedovernight. Foaming with a kitchen whipping machine (Kitchen Aid)resulted in a gas volume fraction of approximately 65 vol %. Drops of5-10 mm diameter of the foam were deposited onto a Telfon plate anddried at 150 W and 60° C. for 30 minutes with an additional beakerinside the oven cavity filled with 500 mL water for higher humidity.

The resulting stiff sponge structure particles absorbed water withoutdisintegrating and softened when filled with water. When in contact withoil, the sponge structures absorbed the oil without disintegrating butremained brittle.

Example 7

Production of Sponge Spheres in Moulds

The foam was prepared as described in Example 6. The foam wastransferred into praline moulds with a diameter of about 15-30 mm anddried at 150 W and 60° C. for 30 minutes with an additional beakerinside the oven cavity filled with 500 mL water for higher humidity. Theresulting stiff sponge structure spheres absorbed water withoutdisintegrating and softened when filled with water. When in contact withoil, the sponge structures absorbed the oil without disintegrating butremained brittle.

Example 8

Production of a Partly Dried Sponge-Like Formulation

The foam was prepared as described in Example 6. The foam wastransferred into cylinders as in Example 1 and dried at 100 W and 60° C.for 15 minutes. The resulting sponge formulation had a moisture contentof approximately 50% and absorbed water and oil without disintegrating.The liquid absorption capacity for water was approximately 6 g/g sampleand for oil 3 g/g sample.

List of literature

-   (1) CN 108273476 A-   (2) WO 2015/056273-   (3) Duan, Bo, et al. “Hydrophobic modification on surface of chitin    sponges for highly effective separation of oil” ACS applied    materials & interfaces 6.22 (2014): 19933-19942-   (4) Jiang, Feng, and You-Lo Hsieh. “Amphiphilic superabsorbent    cellulose nanofibril aerogels”, Journal of Materials Chemistry A    2.18 (2014): 6337-6342-   (5) Zhu, Haiguang, et al. “A robust absorbent material based on    light-responsive superhydrophobic melamine sponge for oil recovery.”    Advanced Materials Interfaces 3.5 (2016): 1500683-   (6) M. Betz, C. A. Garcia-Gonzalez, R. P. Subrahmanyam, I.    Smirnova, U. Kulozik, Preparation of novel whey protein-based    aerogels as drug carriers for life science applications, The Journal    of Supercritical Fluids, Volume 72, 2012, Pages 111-119, ISSN    0896-8446-   (7) Selmer, Ilka, et al. “Development of egg white protein aerogels    as new matrix material for microencapsulation in food.” The Journal    of Supercritical Fluids 106 (2015): 42-49-   (8) V. Perez-Puyana, M. Felix, A. Romero, A. Guerrero, Development    of eco-friendly biodegradable superabsorbent materials obtained by    injection moulding, Journal of Cleaner Production, Volume 198, 2018,    Pages 312-319, ISSN 0959-6526

1. A method of making a porous sponge-like formulation that can absorbwater and oil, said method comprising the steps: a. Preparing a 5-60 wt% protein dispersion in aqueous liquid, preferably in water; b.Dispersing gas in the protein dispersion to form a foam structure; c.Optionally moulding or shaping to form a foam structure; d. Expansion ofthe foam structure; e. Volumetric heating induced water evaporation andprotein denaturation; f. Optionally drying; and g. Optionally cuttinginto pieces.
 2. The method according to claim 1, wherein about 10-50 wt% protein dispersion is prepared in water.
 3. The method according toclaim 1, wherein gas is dispersed in the protein dispersion using arotating membrane foaming device.
 4. The method according to claim 1,wherein said foam structure has a gas volume fraction of 10-90 vol %,preferably 40-80 vol %, most preferably 60-75 vol %.
 5. The methodaccording to claim 1, wherein heating and/or drying is volumetricpreferably through application of electromagnetic waves, preferablymicrowave, most preferably with superposition of convection heating. 6.The method according to claim 1, wherein the temperature gradientbetween the core and the surface layer of the foam structure is between−0.1 to 0.3, preferably from −0.1 to 0.1 and the foam structuretemperature is above the denaturation temperature of the protein duringheating.
 7. The method according to claim 1, wherein a vacuum is appliedbefore and/or during drying which is between 10-800 mbar, preferably50-500 mbar, more preferably between 100-300 mbar.
 8. The methodaccording to claim 1, wherein said porous sponge-like formulation hasopen pores having an average pore size diameter of up to 500 microns,preferably up to 200 microns.
 9. A porous sponge-like formulationcomprising protein, obtained by a method according to claim
 1. 10. Aporous sponge-like formulation that can absorb water, oil and organicsolvent and comprises protein, wherein the said formulation has aporosity of between 10-95 vol %, and wherein said formulation can absorbwater and oil without disintegrating or dissolving to an extent of lessthan 10 wt %.
 11. The porous sponge-like formulation according to claim9, wherein said formulation further comprises soluble and/or non-solublefibre and/or polysaccharides.
 12. The porous sponge-like formulationaccording to claim 9, wherein said formulation is capable of absorbingwater and oil at substantially the same velocity, preferably up to 5mm/s, and wherein the absorbed water, oil and organic solvent can beremoved by compression or suction and re-absorbed into the same saidformulation.
 13. The porous sponge-like formulation according to claim 9wherein said formulation is capable of absorbing water with atemperature of 0-100° C. to an extent that up to 140%, preferably 160%,of pore volume is filled with water due to additional structuralswelling effects.
 14. The porous sponge-like formulation according toclaim 9 wherein said formulation is capable of absorbing oil with atemperature of 0-200° C. to an extent that 90% of pore volume,preferably up to 95% of pore volume, most preferably up to 100% of thepore volume is filled with oil.
 15. The porous sponge-like formulationaccording to claim 9 wherein said formulation is elastically andplastically deformable after absorption of water and is brittle insubstantially dry state and after absorption of oil.
 16. Use of theporous sponge-like formulation according to claim 9 in a product,applied in one of the areas of medicine, pharmacology, biotechnology,chemistry as well as in home care, wound care, (agro-) environmental andconstruction material applications.
 17. Use of the porous sponge-likeformulation according to claim 9 as filter and/or absorber for thecleaning of watery and/or oil-based fluid systems and/or water/oilmixtures.
 18. Use of the porous sponge-like formulation according toclaim 9 as immobilization carrier for microorganisms inbiotechnological, pharmaceutical and/or medical applications
 19. Use ofthe porous sponge-like formulation according to claim 9 for wound caretreatment with high absorbance for wound secretion fluid and tailoredrelease of substances or drugs for the wound related treatment.
 20. Useof the product according claim 9 for medical surgery applications toenable larger amounts of blood or secretion fluid uptake.
 21. Use of theproduct according to claim 9 for cosmetics applications withwater/oil-based liquid and skin care ingredients or skin cleaning fluidsrelease from and/or uptake into the sponge-like product.
 22. Use of theproduct according to claim 9 for the encapsulation of active/functionalingredients from the categories: flavors, aromas, micronutrients,antioxidants, agro-chemicals, chemicals, washing agents, drugs,pre-/probiotic cultures, skin care components, cleaning components. 23.Use of the product according to claim 9 as template (3) for cellculturing
 24. A product comprising the foamed sponge-like formulation ofclaim 9.